Heating apparatus



s. SMlTH. Heating Apparatgs.

Patented July. 31, 1866.

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4 is a vertical section of a tire-chamber con- PATENT -OFFlCE@ SIDNEY SMITH, OF GREENFIELD, MASSACHUSETTS.

HEATING A'PPARATUS.

Specification forming part of Letters Patent No. 56,816, dated July 31, 1866.

To all whom it may concern:

Be it known that I, SIDNEY SMITH, of Greenfield, in the county of Franklin and State of Massachusetts, have invented certain new and useful Improvements in Heating Apparatus, whereby a perfect combustion of the gaseous products of the fuel may be secured; and I do hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings in which- Figure 1 is a vertical section through the center of a stove constructed according to my plan. Fig. 2, is a horizontal plan of the same on line 00 a; of Fig. 1. Fig. 3 is a perspective view of a portion of a fire-chamber, showing central tube and internal construction. Fig.

structed accordingto my plan, applied to a steam-boiler. I

Before giving a minute description of the construction and operation of my apparatus, I deem it proper briefly to recount the principles upon which the results attained dependprinciples which have hitherto been unrecognized and unknown-and to point out the difference which exists between them and the principles controlling all the methods hitherto in use.

I have discovered that in order to produce perfect combustion within the firechamber of a stove or furnace itis necessary to convert the fuel into a gaseous form Without admixture with nitrogen, and to produce the most thorough mingling of these inflammable gases with the supporter of combustion by introducing the latter to the former at a high degree of temperature and in the most minutelydivided condition only; and my invention consists, first, in constructing the fire-chamber of a stoveor furnace in such a manner that the fuel shall be almost or entirely converted into gas before being brought in contact with the oxygen required to produce combustion; and, second, in constructing the walls of the firechamber so that the atmospheric air shall be introduced throughout the extent of the walls in a great number of minute streams at a high temperature, and thus most thoroughly mingled with the inflammable gases from the fuel.

Reference is here made only to that continuous process carried on in stoves and furnaces for the purpose of converting fuel into heat. Under this restriction what is ordinarily termed combustion consists of two processes: first, destructive distillation, by which fuel is converted from a solid or a liquid into a gaseous form; and, second, true combustion, which is the chemical union of those resultant gases with the oxygen of the atmosphere.

By all methods hitherto discovered it has been required that the largest possible volume of air should be passed through the mass of fuel to produce the best result, and it has never been possible to introduce sufficient oxygen to consume the whole quantity of gas generated by the first-named process, because oxygen composes only one-fifth part of the volume of the atmospheric air introduced, and the remaining four-fifths (nitrogen) displaces and carries with it unconsumed a proportionate volume of the inflammable gas from the fuel.

The volume of gas generated depends upon the vehemence of the combustion, the vehemence of combustion depends upon the quantity of oxygen brought in contact with the incandescent gas from the fuel within a given time, and the quantity of oxygen depends upon the volume of atmospheric air introduced, and every atom of oxygen which unit-es with any substance for which it has an affinity liberates and sets free four atoms of nitrogen, so that the more vehement the combustion the greater will be the quantity of nitrogen set free and the greater will be the quantity of inflammable gas which will pass off unconsumed.

By the principles underlying my discovery these results are radically changed. Instead of the largest possible volume of atmospheric air admitted to the fuel, I exclude it entirely, or admit only sufficient to maintain incandescence.

By the methods hitherto in use the gases unconsumed in the midst of the fuel, or by the oxygen which passes through the mass of fuel, rise diluted with many times their own volume of free nitrogen. By my methods they rise nearly or quite free from nitrogen, and therefore in the most favorable condition to unite in combustion with the oxygen of the atmosphere.

Nitrogen is totally deficient in power to support combustion, and, as is abundantly proved by the phenomena of combustion in pure oxymixed with nitro-glycerine.

z sasnc gen gas and in atmospheric air, its presence merely impedes combustion. This is not because the oxygen is less active, but because the atoms of nitrogen will be interposed between the atoms of oxygen and the atoms of the object of its affinity. This result is strikingly illustrated by the effect of powdered glass mixed with gunpowder or woodspirit It follows, then, as a matter perfectly evident that the larger the amount of nitrogen present the greater will be the difficulty of combustion, and if the inflammable gases distilled from the incandescent fuel in the fire-chamber rise diluted with free nitrogen those gases will unite less readily than would be the case were the free nitrogen not present.

By confining the supply of air to the fuel to a quantity sufficient only to maintain incandescence, distillation is effected without combustion, and the resultant gases rise from the fuel by their own levity only and in a condition almost free from nitrogen. When the gases are ignited by mixture with the oxygen of the atmosphere immediately above the fuel the supply of air to the mass of fuel may be entirely out off, the heat from the burning gas then being suificient to maintain incandescence.

The intensity of combustion depends upon the rapidity of the union of the inflammable gases with the oxygen of the atmosphere, and the rapidity of this union depends upon the facility with which they are brought in contact and caused to mingle and the equality of their temperatures.

Homogeneous union is effected with facility in proportion to the minuteness of the subdivision of the elements to be united, and in the case of gases equality in temperature is also important, as is evidenced by the apparent difficulty with which currents of air unite with each other when they differ in temperature; and in the matter of combustion the advantage of the introduction of heated oxygen is abundantly proved by the hot-blast of Neilson.

From these premises it will be apparent that if the fuel be converted into gas, and that gas, without any previous mixture with free nitrogen, be brought in contact with atmospheric air at a high temperature and in minute streams, perfect combustion must be produced, and it is to carry out in practice these principles that my invention has been made.

Having now set forth the nature of my discovery and invention, and having indicated the natural laws or principles upon which it depends and pointed out the difference existing between them and the principles hitherto recognized, I will describe a stove constructed according to and embodying these principles, reserving to myself the right to make separate application for Letters Patent for such modifications of construction as may seem to me desirable, in view of the application of my discovery to special purposes.

The wall A of the fire-chamber is constructed of any suitable material, but from motives of economy I prefer cast-iron. This wall is throughout its extent perforated with as large a number of minute holes as the material used will permit to be made.

The wall A may be constructed with as many parts or sections as may be necessary or convenient, and to relieve it in expanding and contracting I think it advisable to make it corrugated vertically, as shown.

The fire-chamber may be round, square, or in any other form required.

For convenience in removing ashes, 850., without extinguishing the fire, a grate, B, is placed at the bottom of the fire chamber. This grate has beneath it a tight chamber, 0, with a movable bottom, D. When ashes accumulate upon the grate they are shaken through by any convenient means into the chamber (3, from which they may be removed as convenient.

The bottom D is designed to be kept closed except while permitting the ashes within the chamber 0 to escape, as it is not desired that any draft should ever be permitted to enter through the grate B.

The wall A, I find it convenient to construct in the following manner: From the back of the pattern I make indentations, as numerous as possiblewithout weakening the casting. These indentations extend nearly through to the front surface, and mark the positions of the perforations which admit the air to support combustion within the fire chamber. When the casting from this pattern is completed the perforations are made by a hammer andpunch, a slight blow being sufficient to break through the film which covers the indentations. By this means the edges of the perforations are made ragged and uneven, which has proved very beneficial, as the en tering current is broken up thereby. At a distance of two or three inches from the bottom is the flange E, projecting oneehalf or three-fourths of an inch from the highest points'of the back surface; or I sometimes prefer to make the lower part of the wall without perforations, as shown at F, Fig. 4E. Surrounding the wall A, and at a distance of half or three-fourths of an inch therefrom, I place the jacket G, which may be made of thin metallic plates perforated with a great number of minute holes. Ordinary perforated tin having holes about one sixty-fourth of an inch in diameter, and placed as close together as possible, answers the required conditions of this jacket very Well. Between this jacket G and the outer case or wall, H, is a space of four or five inches, or more in large structures, into which the external air is admitted through any suitable arrangement of valves which are susceptible of adjustment and control. This I accomplish in the stove represented in Figs. 1, 2, and 3 by perforating the bottom plate, I, and covering it with the flat valvering J, by the movement of which the per-' forations through the plate I may be partially or wholly closed.

If the flange E is employed and the lower portion of the wall A is perforated, the space between the wall A and the jacket G will be divided by said flange E into two apartments, K and L, and around the lower part of the jacket G is placed the valve-ring M, by means of which the orifices through the jacket into the apartment L may be closed. This valvering may be operated by the rod N, or by any other suitable and convenient means.

The upper edges of the wallAand jacket G are to be joined tothe side or case H by the plate 0, or its equivalent, and there should be no openings through the upper part of case H excepting such as are necessary for the purpose of admitting fuel, &c., and such openings should be constructed so as to close very tightly and not admit air direct from the surrounding atmosphere.

When I desire a fire in my stove a small quantity of fuel is placed in the chamber and lighted in the ordinary way. If coal is the fuel used, the quantity should not exceed that required to cover'the bottom of the fire-chamber to a depth of two or three inches, unless the heater be very large.

All accesss of draft is cut off except through the perforations of the walls. As the volume of air permitted to pass through the fuel is 7 very small the combustion thereis barely sufficient to raise the mass of fuel to a degree of temperature sufficient to produce destructive distillation. The gases which are set free by this process rise by their own levity, and, mixing with the atmospheric air which enters through the perforated walls above the'fuel, become ignited and consumed. The combustion of this free gas within the fire-chamber very soon heats the wall A, so that the air passing through its perforations is heated to a certain degree before coming in contact with the hot gases within; but no single wall will raise the temperature of the air passing through its perforations to a temperature sufl'iciently high to secure the most rapid and vehement combustion.

Atmospheric air is a bad conductor of heat, or, in other words, does not absorb heat readily. It is excessively elastic and mobile, and hence the simple presence of a very hot body will not, unaided, quickly raise the temperature of the surrounding air.

To produce perfect combustion it is required that the oxygen to support the combustion should be raised to a temperature as nearly equal to the temperature of the gas to be consumed as possible, and to so raise its temperature means must be provided by which the required caloric may be imparted almost instantaneously. Those means are provided in the use of the perforated jacket G, which possesses two essential functions: First, it incloses a narrow space in which there can be but little flow and counter-flow of the confined air in currents; hence the radiated caloric is not carried away to be distributed through a large volume of air, and that which has passed through this thin sheet is reverberated from the inner surface of the jacket. Second, it is perforated with. a very large number of minute holes, through which the air flows in minute streams in to the intensely-heated space K, each atom of oxygen being, as it were, separated from the rest and submitted individually to the heating process. That caloric will be absorbed much more rapidly in this minutelydivided state than it would be were large volumes exposed does not admit of a question. When this heated air flows through the perforations in the wall A the most vehement combustion results. From every orifice streams of flame, varying in length from one or two inches to two or three feet, curl and twist like tortured serpents.

The more numerous and the more minute the perforations through the wall A the more intense and vehement is the combustion, so that an experimental wall made of iron minutely perforated by puncturing was melted and destroyed in a few minutes.

The state of art, therefore, precludes the possibility of obtaining by these .means the very highest degree of intensity in the combustion ot'fuelan ultimatum which, in practice, can only be obtained when some substance can be economically used which possesses power to withstand the most intense heat and still preserve its formwhen perforated as described.

From the foregoing description it will appear that the opposite walls of the fire-chamber should not be so far removed from each other as to prevent the jets of air entering from each side meeting in the center; but in large structures, as the fire-boxes of steam-boilers, &c., it would be manifestly inconvenient, if not impossible, to retain these narrow limits. I therefore erect towers, like P, Figs. 3 and 4, in the midst of the fire-chamber. They may be in number as many as required, according to the size of the fire-chamber. They are constructed exactly like the walls A, and have within them the finely-perforated wall G, air being admitted through the central space, Q, in the same manner as that already described.

The character of the combustion produced by my apparatus is very marked. It bears every feature of combustion in pure oxygen gas, for on throwing small bits of shavings or particles of sawdust or iron-filings into the flame hundreds of brilliant sparks or scintillations'(which every chemist has observed on lowering particles of carbon or iron into a jar of pure oxygen) are given out.

There are other evidences of the separation of the oxygen from the nitrogen of the atmosphereimmediately after entering the fire-chamber, for immediately after passing through the perforations a space was observable between the inner surface of the fire-pot and the point at which the spiral flames commenced, where there was no combustion. Now, it is evident that this space cannot be filled with combustible'gases, inasmuch as there are jets of air constantly passing through this space, all of which are heated above the point of ignition, causing these to ignite.

The separation of the oxygen and nitrogen of the atmosphere immediately on entering the fire-chamber has an important tendency to preserve the walls A, which do not become so hot, and therefore do not oxidize in the vicinity of the perforations as rapidly as would otherwise be the case.

I am aware that air has been admitted above the fuel in a variety of methods for the purpose of burning the inflammable gases which would otherwise escape unconsumed; and I am also aware that air has been admitted through perforations in the wall of the firepot, and through tubes erected upon the grate; but, as I have explained, the operation of all of these plans is radically different from mine, herein set forth.

I am not aware that a double wall such as described has ever been used, or that the effect of it has ever been otherwise attained.

I am not aware that afire-pot with a closed bottom has ever been used, or that the same effect has ever been attained in the combustion of fuel.

The advantage of my apparatus is the complete and perfect combustion of the gaseous products of the fuel, giving out at least eight times the quantity of heat obtained by any other method, or amounting to a saving of seven-eighths of the fuel required to produce a given quantity of heat, and with any proportionate loss in the durability of the apparatus.

Having set forth my discovery and the principles upon which it depends, and having described the principles of construction and the operation of an apparatus capable of carrying the principles of my discovery into effect, what I claim as new, and desire to secure by Letters Patent, is

1. A fire-chamber constructed in accordance with the principles and substantially in the manner herein set forth.

2. The combination of the perforated walls A and G, constructed as described, to form a fire-chamber.

3. The combination of the perforated walls A and G with the close bottom D, substantially as and for the purpose set forth.

4. The combination of the perforated walls A and G with the partition E and damper M, substantially as and for the purpose set forth.

SIDNEY SMITH. 

